JavaScript date_format() function – Convert datetime like Php

Php has a date_format() function which can convert the datetime into any custom format. But sadly javascript do not have any such thing. So, we have implemented one for it. Although, there are many wonderful libraries like moment.js to deal with datetime but sometimes we just want simple and lightweight solution. With this function, you can easily get any javascript date format.

(function () {
  // Defining locale
  Date.shortMonths = ['Jan', 'Feb', 'Mar', 'Apr', 'May', 'Jun', 'Jul', 'Aug', 'Sep', 'Oct', 'Nov', 'Dec']
  Date.longMonths = ['January', 'February', 'March', 'April', 'May', 'June', 'July', 'August', 'September', 'October', 'November', 'December']
  Date.shortDays = ['Sun', 'Mon', 'Tue', 'Wed', 'Thu', 'Fri', 'Sat']
  Date.longDays = ['Sunday', 'Monday', 'Tuesday', 'Wednesday', 'Thursday', 'Friday', 'Saturday']
  // Defining patterns
  var replaceChars = {
    // Day
    d: function () { var d = this.getDate(); return (d < 10 ? '0' : '') + d },
    D: function () { return Date.shortDays[this.getDay()] },
    j: function () { return this.getDate() },
    l: function () { return Date.longDays[this.getDay()] },
    N: function () { var N = this.getDay(); return (N === 0 ? 7 : N) },
    S: function () { var S = this.getDate(); return (S % 10 === 1 && S !== 11 ? 'st' : (S % 10 === 2 && S !== 12 ? 'nd' : (S % 10 === 3 && S !== 13 ? 'rd' : 'th'))) },
    w: function () { return this.getDay() },
    z: function () { var d = new Date(this.getFullYear(), 0, 1); return Math.ceil((this - d) / 86400000) },
    // Week
    W: function () {
      var target = new Date(this.valueOf())
      var dayNr = (this.getDay() + 6) % 7
      target.setDate(target.getDate() - dayNr + 3)
      var firstThursday = target.valueOf()
      target.setMonth(0, 1)
      if (target.getDay() !== 4) {
        target.setMonth(0, 1 + ((4 - target.getDay()) + 7) % 7)
      }
      var retVal = 1 + Math.ceil((firstThursday - target) / 604800000)

      return (retVal < 10 ? '0' + retVal : retVal)
    },
    // Month
    F: function () { return Date.longMonths[this.getMonth()] },
    m: function () { var m = this.getMonth(); return (m < 9 ? '0' : '') + (m + 1) },
    M: function () { return Date.shortMonths[this.getMonth()] },
    n: function () { return this.getMonth() + 1 },
    t: function () {
      var year = this.getFullYear()
      var nextMonth = this.getMonth() + 1
      if (nextMonth === 12) {
        year = year++
        nextMonth = 0
      }
      return new Date(year, nextMonth, 0).getDate()
    },
    // Year
    L: function () { var L = this.getFullYear(); return (L % 400 === 0 || (L % 100 !== 0 && L % 4 === 0)) },
    o: function () { var d = new Date(this.valueOf()); d.setDate(d.getDate() - ((this.getDay() + 6) % 7) + 3); return d.getFullYear() },
    Y: function () { return this.getFullYear() },
    y: function () { return ('' + this.getFullYear()).substr(2) },
    // Time
    a: function () { return this.getHours() < 12 ? 'am' : 'pm' },
    A: function () { return this.getHours() < 12 ? 'AM' : 'PM' },
    B: function () { return Math.floor((((this.getUTCHours() + 1) % 24) + this.getUTCMinutes() / 60 + this.getUTCSeconds() / 3600) * 1000 / 24) },
    g: function () { return this.getHours() % 12 || 12 },
    G: function () { return this.getHours() },
    h: function () { var h = this.getHours(); return ((h % 12 || 12) < 10 ? '0' : '') + (h % 12 || 12) },
    H: function () { var H = this.getHours(); return (H < 10 ? '0' : '') + H },
    i: function () { var i = this.getMinutes(); return (i < 10 ? '0' : '') + i },
    s: function () { var s = this.getSeconds(); return (s < 10 ? '0' : '') + s },
    v: function () { var v = this.getMilliseconds(); return (v < 10 ? '00' : (v < 100 ? '0' : '')) + v },
    // Timezone
    e: function () { return Intl.DateTimeFormat().resolvedOptions().timeZone },
    I: function () {
      var DST = null
      for (var i = 0; i < 12; ++i) {
        var d = new Date(this.getFullYear(), i, 1)
        var offset = d.getTimezoneOffset()

        if (DST === null) DST = offset
        else if (offset < DST) { DST = offset; break } else if (offset > DST) break
      }
      return (this.getTimezoneOffset() === DST) | 0
    },
    O: function () { var O = this.getTimezoneOffset(); return (-O < 0 ? '-' : '+') + (Math.abs(O / 60) < 10 ? '0' : '') + Math.floor(Math.abs(O / 60)) + (Math.abs(O % 60) === 0 ? '00' : ((Math.abs(O % 60) < 10 ? '0' : '')) + (Math.abs(O % 60))) },
    P: function () { var P = this.getTimezoneOffset(); return (-P < 0 ? '-' : '+') + (Math.abs(P / 60) < 10 ? '0' : '') + Math.floor(Math.abs(P / 60)) + ':' + (Math.abs(P % 60) === 0 ? '00' : ((Math.abs(P % 60) < 10 ? '0' : '')) + (Math.abs(P % 60))) },
    T: function () { var tz = this.toLocaleTimeString(navigator.language, {timeZoneName: 'short'}).split(' '); return tz[tz.length - 1] },
    Z: function () { return -this.getTimezoneOffset() * 60 },
    // Full Date/Time
    c: function () { return this.format('Y-m-d\\TH:i:sP') },
    r: function () { return this.toString() },
    U: function () { return Math.floor(this.getTime() / 1000) }
  }

  // Simulates PHP's date function
  Date.prototype.format = function (format) {
    var date = this
    return format.replace(/(\\?)(.)/g, function (_, esc, chr) {
      return (esc === '' && replaceChars[chr]) ? replaceChars[chr].call(date) : chr
    })
  }
}).call(this);

function date_format(dateVal, formatVal){
    return dateVal.format(formatVal);
}

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Using JS date_format()

This function expects two parameters – Date and Format string. You may create date using any method which javascript supports like timestamp milliseconds or datetime string. It just requires the date obj.

var dateVal = new Date();
date_format(dateVal, 'd-m-Y');
// Output: 21-12-2020

This can also convert a string in to unix timestamp or datetime javascript format.

Date Format String Table

Format character	Description	Output
Day
d	Day of the month, 2 digits with leading zeros	01 to 31
D	A textual representation of a day, three letters	Mon through Sun
j	Day of the month without leading zeros	1 to 31
l (lowercase L)	A full textual representation of the day of the week	Sunday through Saturday
N	ISO-8601 numeric representation of the day of the week	1 (for Monday) through 7 (for Sunday)
S	English ordinal suffix for the day of the month, 2 characters	st, nd, rd or th. Works well with j
w	Numeric representation of the day of the week	0 (for Sunday) through 6 (for Saturday)
z	The day of the year (starting from 0)	0 through 365
Week
W	ISO-8601 week number of year, weeks starting on Monday	Example: 42 (the 42nd week in the year)
Month
F	A full textual representation of a month, such as January or March	January through December
m	Numeric representation of a month, with leading zeros	01 through 12
M	A short textual representation of a month, three letters	Jan through Dec
n	Numeric representation of a month, without leading zeros	1 through 12
t	Number of days in the given month	28 through 31
Year
L	Whether it’s a leap year	1 if it is a leap year, 0 otherwise.
o	ISO-8601 year number. This has the same value as Y, except that if the ISO week number (W) belongs to the previous or next year, that year is used instead.	Examples: 1999 or 2003
Y	A full numeric representation of a year, 4 digits	Examples: 1999 or 2003
y	A two digit representation of a year	Examples: 99 or 03
Time
a	Lowercase Ante meridiem or Post meridiem	am or pm
A	Uppercase Ante meridiem or Post meridiem	AM or PM
B	Swatch Internet time	000 through 999
g	12-hour format of an hour without leading zeros	1 through 12
G	24-hour format of an hour without leading zeros	0 through 23
h	12-hour format of an hour with leading zeros	01 through 12
H	24-hour format of an hour with leading zeros	00 through 23
i	Minutes with leading zeros	00 to 59
s	Seconds, with leading zeros	00 through 59
v	Milliseconds	Example: 654
Timezone
e	Timezone identifier	Atlantic/Azorest or Europe/Amsterdam
I (capital i)	Whether or not the date is in daylights savings time	1 if Daylight Savings Time, 0 otherwise.
O (capital o)	Difference to Greenwich time (GMT) in hours	Example: +0200
P	Difference to Greenwich time (GMT) with colon between hours and minutes	Example: +02:00
T	Timezone setting of this machine	Examples: EST or MDT
Z	Timezone offset in seconds. The offset for timezones west of UTC is always negative, and for those east of UTC is always positive.	-43200 through 43200
Full Date/Time
c	ISO 8601 formatted date	Example: 2017-11-26T15:12:21+00:00
r	RFC 2822 formatted date	Example: Thu, 21 Dec 2000 16:01:07 +0200
U	Seconds since the Unix Epoch (January 1 1970 00:00:00 GMT)	Example: 1501804996

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Examples

Format – YYYY-MM-DD HH-mm-ss

var dateVal = new Date();
date_format(dateVal, 'd-m-Y H:i:s');

Format – Dec 21st, 2020

var dateVal = new Date();
date_format(dateVal, 'M jS, Y');

Format – Today is 21-12-2020

var dateVal = new Date();
date_format(dateVal, '\\T\\o\\d\\a\\y \\i\\s d-m-Y');

Format – Unix Timestamp (milliseconds)

var dateVal = new Date();
date_format(dateVal, 'U') * 1000;

Format – Twitter feed tweet post time

This example will help you in getting the comparison of dates. When somebody posts a tweet on tweeter feed or Facebook post or Instagram photo or comments anywhere, they use to show the time since it was posted. This time could be in seconds, minutes, even weeks or months. Our date_format() function can help in getting that too.

var currentTime = Date.now();
var commentPostTime = new Date('2020-12-22 00:12:43');

var timePassedAfterCommentInSeconds = currentTime - commentPostTime;